The present invention relates to a two-port valve suitable for use in a duct for fluid including foreign matter.
In a two-port valve in which a valve seat formed inside and around a connecting hole on an input port side is opened and closed by a valve body facing the valve seat to come in contact with and separate from the valve seat in a casing, it is possible to increase a size of a flow path section. However, if the two-port valve is used in a duct for fluid including a large amount of foreign matter such as refuse, the foreign matter gets tangled with the valve body or a valve shaft or builds up in a portion of the flow path, which may make the two-port valve unusable. Therefore, a ball valve or the like which can prevent the foreign matter from getting tangled is used in the duct for the fluid including the large amount of foreign matter but the ball valve or the like is relatively expensive. Therefore, development of a product by which the foreign matter can be prevented from getting tangled or building up by an inexpensive pilot-type two-port valve or the like is desired.
The present invention has been accomplished for development of such a product. Therefore, it is basically a technical object of the invention to provide an inexpensive two-port valve with a simple structure in which foreign matter does not get tangled with a valve body or a valve shaft or does not build up in a portion of a flow path when the two-port valve is used in a duct for fluid including a large amount of foreign matter such as refuse.
It is another technical object of the invention to provide a two-port valve in which the valve body can be easily inserted and detached from outside a casing and which has excellent assembling property, disassembling property, and maintainability of the valve body which is liable to be damaged by the foreign matter such as refuse.
To achieve the above objects, a two-port valve of the invention comprises: an input port and an output port provided in a tip end face and a side face of a casing in orientations at 90xc2x0 from each other; a flow path for connecting both the ports; an input-side connecting hole for connecting the input port to the flow path; an output-side connecting hole for connecting the output port to the flow path; an annular valve seat formed around the input-side connecting hole; a valve body for opening and closing the valve seat from an inside of the flow path; and a valve shaft in a circular-cylindrical shape inserted for forward and rearward movements in a sealed state into a sliding hole in the casing, having a tip end portion facing the inside of the flow path, having the valve body at the tip end portion, and for operating such that the valve body moves across the output-side connecting hole in opening and closing of the valve seat by the valve body, wherein the valve shaft has a diameter equal to or slightly larger than that of the valve body and a stroke of the valve body for opening and closing the valve seat is an amount required to fully open the output-side connecting hole.
In the two-port valve having the above structure, a flow path section can be set at a sufficiently large size but the opening and closing stroke of the valve body is set at the amount required to fully open the output-side connecting hole. Therefore, the flow path extending from the input port to reach the output port in the casing becomes a maximum size when the valve is open and a vortex-shaped flow is suppressed. If the two-port valve is used in the duct for fluid including a large amount of foreign matter such as refuse, the foreign matter does not build up in the flow path.
Furthermore, because the diameter of the valve shaft projecting and sinking from and into the casing into and from the flow path is set to be equal to or slightly larger than the diameter of the valve body, a stagnation portion or a portion where the foreign matter gets tangled with the valve body is not generated in the flow path in the casing, which also prevents the foreign matter from building up in the flow path.
Because the two-port valve is formed by structurally modifying a conventionally known pilot-type valve, the two-port valve has the simple structure and can be provided at a low price as compared with a ball valve or the like conventionally used for fluid including the foreign matter.
According to a concrete embodiment of the invention, the input-side connecting hole and the output-side connecting hole respectively have sizes similar to those of the input port and the output port and a length of the flow path in an axial direction of the valve shaft is similar to a diameter of the output-side connecting hole in the axial direction.
The valve body and the valve shaft may be formed separately or connected to each other or may be formed integrally.
According to another concrete embodiment of the invention, the sliding hole is formed to extend from a rear end face of the casing to reach the flow path, the valve shaft is inserted into the sliding hole from a rear end face side of the casing, a cover is detachably mounted to the rear end face of the casing, a piston for operating by operation of pilot fluid pressure is housed in the cover, the valve shaft is connected to the piston, and the valve shaft and the valve body can be mounted into and detached from the sliding hole from the rear end face side of the casing in a state in which the cover is detached.
If the valve shaft and the valve body can be inserted and detached into and from the sliding hole from outside the casing as described above, an assembling property, a disassembling property, and maintainability of the valve body which is liable to be damaged by the foreign matter such as refuse become excellent.
It is preferable that a scraper for suppressing entering of foreign matter from the flow path into the sliding hole is provided in a position of the sliding hole close to an end portion on a flow path side.